This invention relates generally to processing document images. More specifically the invention relates to image distortion correction in document images.
As more and more documents and images are transferred to computer-readable mediums, distortion of the original documents can occur. Be it from the method of imaging the document, or the particular device or program being used, distortion problems beyond mere rotational issues are frequent.
Many traditional and present deskewing programs are unable to correct image distortion. Despite the program being referenced for so-called “deskewing,” the algorithms applied are unable to effect more than a re-alignment of the image, as opposed to an actual correction of the image itself. While rotational correction may be sufficient for some document transfers where a direct scan of the document is all that occurs, for many other imaging applications such a correction would be insufficient. For example, when a transformation is applied to a digital image, such as scaling, rotating, or scanning, perspective and projective distortions can be introduced. Current correction applications would be unable to correct any such distortion, and hence the document image can be rendered useless due to certain transfer distortions.
Additionally, many of the current programs must be applied on an individual basis to images and documents that can span hundreds, if not thousands of pages. Current programs, in addition to not correcting many distortions, create an excessively cumbersome process by which correcting documents and images occurs. Not only is the user made to determine what documents and images require correction, but the user is then required to individually process each document or image of the series in turn. Such a process can introduce unwanted time and expense that is unacceptable to many business models.
For example, if historical census documents are being transferred from the original census papers, or alternatively from an image of the original census papers such as microfiche, the documents may contain hundreds, thousands, tens of thousands or more pages to be transferred. If every image needed to be individually viewed and then a determination is performed of whether a correction is needed, the entire process could take years to finish. What is needed is an application for detecting and correcting a variety of distortions that can occur in document imaging from multiple sources. The present invention meets this and other needs.